John E

With few exceptions, bikes from the early 1960s came with fairly close-ratio gearing and derailleurs which simply cannot handle a wide range. By the early 1970s we saw various touring derailleurs, including long-cage rears with generous chain takeup capabilities and long-throw fronts which could shift across three chainrings. If you do not mind being non-authentic, you can easily retrofit a SunTour V-GT rear derailleur onto almost any older bike, permitting you to accommodate up to 34 teeth on the rear cogset. If you really need the range, follow the good pastor's advice to look for a bike which already has a triple chainring. If you do not mind gaps in your gear ratio progression (I do), you can match a 50-36 double against a 14-17-21-26-32 freewheel. If you find a bike with a standard-width 6-speed freewheel (126mm overlock rear axle width), you can even retrofit a 7-speed freewheel, such as 14-16-18-21-24-28-32, giving you both wide range and decently close ratios.